Piston.



PATENTED JAN. 15, 1907.

J. IMLER'.

PISTON.

APPLICATION FILED 001211.1904.

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rrurrnn snares rarnnr orrrcri JOSEPH IMLER, OF FORT WAYNE, INDIANA. ASSIGNOR TO JOSEPH H. HOOVER, OF GARRET", INDIANA.

PISTON.

Specification of Letters Patent.

Patented Jan. 15, 1907.

Application filed October 11, 1904. Serial No. 228,045.

T all whom, it nut-y concern:

Be it known that I, JosEPn IMLER, a citizen of the United States, residing at Fort W'ayne, in the county of Allen and State of Indiana, have invented new and useful .lmprovements in Pistons, of which the following is a specification.

This invention relates to pistons for steamengincs, pumps, and the like.

The slide-valves of steam-eng nes as usually constructed are geared to cut oil the exhaust before the piston has reachcd the end of its stroke, with the result that some of the steam to be exhausted is trapped in the cylinder in front of the piston. This trapped steam materially retards the throw of the piston, especially when the expansion of the live steam on the opposite side of the piston has been expended and of less pressure than the trapped steam, and this occurs by virtue of the inlet-port being closed by the slide-valve when the piston has reached about one-half of its stroke, the expansion of the steam being relied upon to carry the piston to the end of its stroke.

It is one of the objects of the present invention to relieve the piston of the back pressure resulting from this trapped. steam and to utilize the latter as a means of replenishing and maintaining a cushioning-chamber in the piston with steam under pressure, so as to prevent friction and dragging of the piston upon the bottom of the cylinder, and at the same time permit this steam to lubricate the wall of the cylinder and the appurtenances c rried by the piston.

For a full understanding of the construction, merits, and advantages of my invention reference is to be had to the following description and the accompanying drawings, wherein Figure 1 is a longitudinal vertical section through a steam-engine cylinder and through my improved piston which is mounted therein and showing in dotted lines the position of the piston at its point of impact with the trapped steam in one end of the cylinder. Fig. 2 is a plan view of one of the hollow sections of which the piston is composed. Fig. 3 is a detail in perspective of the improved valve.

Making renewed reference to the drawings, wherein like characters of notation indicate corresponding parts appearing in the several illustrations, 1 designates the cylinder of an ordinary steam-engine, and 2 a sliding valve therefor, which is geared to operate in the usual manner to control the inlet and exhaust of the steam for the cylinder.

The usual inlet-ports 3 3 and exhaust-orifice 4 are shown in Fig. 1, and, as is well known, these orifices are controlled by the reciprocation of the slide-valve, which has the usual cup 5.

My improved piston is composed of two sections or disk members 6 and 7, each of which is channeled out or chamfered on its inner face, so as to provide a central annular chamber 8 when these two channeled porrions are fitted together. Each disk portion has a central boss 9 and lugs 10 arranged therearound and provided with openings 11, which receive the clamping-bolts 12, which hold the ends of the bosses and lugs in contact, as shown in Fig. 1. The inner edge of each disk-section is reduced to provide an annular flange 13, which when the two sections are connected forms an outer annular chamber 14 around the piston, the outer side of which is closed by the walls of the cylinder. The ends of these annular flanges 13 terminate short of the ends of the lugs and bosses, so as to provide a comparatively small opening or space 15 between the contiguous edges of the flanges and by means of which a communication is established between the central annular chamber 8 in the piston and the outer annular chamber 14 therearound; but the flanges 13 also serve to substantially separate the two chambers. Upon each side of the outer annular chamber'14 are the usual packing-rings 16 and 17, which prevent the escape of the' steam from one side of the piston to the other and also from the chamber 14.

Each of the piston-sections has an opening 17, which extends from the central chamber 8 to the outer side thereof, and when the piston is mounted in the cylinder these openings are in alineinent and preferably near the bottom of the cylinder.

In the central chamber 8 is a bodily-movable reciprocating valve 18. This Valve is formed with a central cylindrical portion 19 the ends 20 of which serve as seating-sun faces for the valve in its reciprocating movernent in the chamber of the piston, and these surfaces are adapted to engage with the inner face of the hollow disk members around the edge of the openings 17 therein. From opposite ends-of the central cylindrical portion project tubular extension-guides 21, and these guides also constitute the conduits or ports for the valve, inasmuch as the steam enters and escapes from the tubular extensions 21 by means of the transverse apertures or auxiliary ports 22, which are arranged in series at the juncture of the extension-guides with the central cylindrical body portion.

The piston is fitted with the usual pistonrod 26, which extends through the central bosses 9 and has a nut 25 upon its end.

From the description thus far given it will be seen that when steam is admitted to the cylinder it will act upon the flat end of the cylindrical portion 19 of the valve, which isat the inner end of the tubular extension, as well as upon the end of the tubular extension, to force the valve open on the livesteam side of the piston and close the ports 22 on the other side of the valve, the seatingsurface 20 of which is in intimate contact with the sides of the disk 7 around the aperture therein, so as to prevent the steam escaping from the chamber 8, which becomes filled with steam under pressure. Some of this steam passes through the space 15, be tween the flanges 13, and enters the annular chamber 141, where it is confined by the pack ing-rings, and during the stroke of the piston the steam in these chambers, and particularly in the outer annular chamber 14, has a tendency to equalize or partially overcome the weight of the piston, so as to cushion the latter and prevent heavy dragging upon the bottom of the cylinder, and thus the chamber 14 may be considered as a cushioningchamber and a reservoir for the lubricant for the walls of the cylinder, inasmuch as the steam acts to lubricate the same. This position of the piston and its valve is shown in Fig. 1, and the slide-valve is then moving to the right and has just uncovered the inletport 3 at the left of the cylinder. It being premised that the slide-valve is geared so as to continue to admit the live steam until the piston has made one-half of its stroke and the exhaust is taking place on the other side of the piston, the balance of the stroke of the piston is supposed to be accomplished by means of the expansion of such live steam, and this expansion carries the piston to about the three-quarter point, which is indicated by the dotted-line position of the piston in Fig. 1 but as the slide-valve had closed the exhaust-port at the half-stroke of the piston some of the steam is gradually compressed by the continued throw of the piston from the expansion of the steam on the opposite side, and when the expansive qualities of the live steam have become expended and less than the pressure of the trapped steam the latter would exert back pressure upon the piston if it were not for my improved valve, which is then moved by the pressure of the trapped steam to open the ports 22 on the other side of the valve, as shown in dotted lines in Fig.

1, and thus admit the trapped steam into the central chamber 8 of the piston and through the space 15 into the annular balancingchamber 14, some of the steam from which has become slightly condensed during its stroke from the center of the cylinder to the three-quarter point. Obviously the same action results upon the next stroke of the piston at the other end of the cylinder.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is

A piston having a central chamber therein, and an outer balancing-chamber in its periphery, separated from the central chamber but in communication therewith, and having also a valve-opening in each of its end walls oppositely disposed; a bodily-movable valve provided with seating-surfaces, adapted respectively to close the corresponding openings; and two packing-rings arranged in the periphery of the piston, one upon either side of said outer annular chamber.

In testimony whereof I aflix my signature in presence of two subscribing witnesses.

' JOSEPH IMLER.

Witnesses O. W. FOWLER, A. A. EGE. 

